/*
 * Library: libcrc
 * File:    src/crc32.c
 * Author:  Lammert Bies
 *
 * This file is licensed under the MIT License as stated below
 *
 * Copyright (c) 1999-2016 Lammert Bies
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * Description
 * -----------
 * The source file src/crc32.c contains the routines which are needed to
 * calculate a 32 bit CRC value of a sequence of bytes.
 */

#include <stdint.h>
#include <stdlib.h>
#include "crc32.h"

/*
 * Include the lookup table for the CRC 32 calculation
 */

static const unsigned int crc_tab32[256] =
{
    0x00000000UL, 0x77073096UL, 0xEE0E612CUL, 0x990951BAUL,
    0x076DC419UL, 0x706AF48FUL, 0xE963A535UL, 0x9E6495A3UL,
    0x0EDB8832UL, 0x79DCB8A4UL, 0xE0D5E91EUL, 0x97D2D988UL,
    0x09B64C2BUL, 0x7EB17CBDUL, 0xE7B82D07UL, 0x90BF1D91UL,
    0x1DB71064UL, 0x6AB020F2UL, 0xF3B97148UL, 0x84BE41DEUL,
    0x1ADAD47DUL, 0x6DDDE4EBUL, 0xF4D4B551UL, 0x83D385C7UL,
    0x136C9856UL, 0x646BA8C0UL, 0xFD62F97AUL, 0x8A65C9ECUL,
    0x14015C4FUL, 0x63066CD9UL, 0xFA0F3D63UL, 0x8D080DF5UL,
    0x3B6E20C8UL, 0x4C69105EUL, 0xD56041E4UL, 0xA2677172UL,
    0x3C03E4D1UL, 0x4B04D447UL, 0xD20D85FDUL, 0xA50AB56BUL,
    0x35B5A8FAUL, 0x42B2986CUL, 0xDBBBC9D6UL, 0xACBCF940UL,
    0x32D86CE3UL, 0x45DF5C75UL, 0xDCD60DCFUL, 0xABD13D59UL,
    0x26D930ACUL, 0x51DE003AUL, 0xC8D75180UL, 0xBFD06116UL,
    0x21B4F4B5UL, 0x56B3C423UL, 0xCFBA9599UL, 0xB8BDA50FUL,
    0x2802B89EUL, 0x5F058808UL, 0xC60CD9B2UL, 0xB10BE924UL,
    0x2F6F7C87UL, 0x58684C11UL, 0xC1611DABUL, 0xB6662D3DUL,
    0x76DC4190UL, 0x01DB7106UL, 0x98D220BCUL, 0xEFD5102AUL,
    0x71B18589UL, 0x06B6B51FUL, 0x9FBFE4A5UL, 0xE8B8D433UL,
    0x7807C9A2UL, 0x0F00F934UL, 0x9609A88EUL, 0xE10E9818UL,
    0x7F6A0DBBUL, 0x086D3D2DUL, 0x91646C97UL, 0xE6635C01UL,
    0x6B6B51F4UL, 0x1C6C6162UL, 0x856530D8UL, 0xF262004EUL,
    0x6C0695EDUL, 0x1B01A57BUL, 0x8208F4C1UL, 0xF50FC457UL,
    0x65B0D9C6UL, 0x12B7E950UL, 0x8BBEB8EAUL, 0xFCB9887CUL,
    0x62DD1DDFUL, 0x15DA2D49UL, 0x8CD37CF3UL, 0xFBD44C65UL,
    0x4DB26158UL, 0x3AB551CEUL, 0xA3BC0074UL, 0xD4BB30E2UL,
    0x4ADFA541UL, 0x3DD895D7UL, 0xA4D1C46DUL, 0xD3D6F4FBUL,
    0x4369E96AUL, 0x346ED9FCUL, 0xAD678846UL, 0xDA60B8D0UL,
    0x44042D73UL, 0x33031DE5UL, 0xAA0A4C5FUL, 0xDD0D7CC9UL,
    0x5005713CUL, 0x270241AAUL, 0xBE0B1010UL, 0xC90C2086UL,
    0x5768B525UL, 0x206F85B3UL, 0xB966D409UL, 0xCE61E49FUL,
    0x5EDEF90EUL, 0x29D9C998UL, 0xB0D09822UL, 0xC7D7A8B4UL,
    0x59B33D17UL, 0x2EB40D81UL, 0xB7BD5C3BUL, 0xC0BA6CADUL,
    0xEDB88320UL, 0x9ABFB3B6UL, 0x03B6E20CUL, 0x74B1D29AUL,
    0xEAD54739UL, 0x9DD277AFUL, 0x04DB2615UL, 0x73DC1683UL,
    0xE3630B12UL, 0x94643B84UL, 0x0D6D6A3EUL, 0x7A6A5AA8UL,
    0xE40ECF0BUL, 0x9309FF9DUL, 0x0A00AE27UL, 0x7D079EB1UL,
    0xF00F9344UL, 0x8708A3D2UL, 0x1E01F268UL, 0x6906C2FEUL,
    0xF762575DUL, 0x806567CBUL, 0x196C3671UL, 0x6E6B06E7UL,
    0xFED41B76UL, 0x89D32BE0UL, 0x10DA7A5AUL, 0x67DD4ACCUL,
    0xF9B9DF6FUL, 0x8EBEEFF9UL, 0x17B7BE43UL, 0x60B08ED5UL,
    0xD6D6A3E8UL, 0xA1D1937EUL, 0x38D8C2C4UL, 0x4FDFF252UL,
    0xD1BB67F1UL, 0xA6BC5767UL, 0x3FB506DDUL, 0x48B2364BUL,
    0xD80D2BDAUL, 0xAF0A1B4CUL, 0x36034AF6UL, 0x41047A60UL,
    0xDF60EFC3UL, 0xA867DF55UL, 0x316E8EEFUL, 0x4669BE79UL,
    0xCB61B38CUL, 0xBC66831AUL, 0x256FD2A0UL, 0x5268E236UL,
    0xCC0C7795UL, 0xBB0B4703UL, 0x220216B9UL, 0x5505262FUL,
    0xC5BA3BBEUL, 0xB2BD0B28UL, 0x2BB45A92UL, 0x5CB36A04UL,
    0xC2D7FFA7UL, 0xB5D0CF31UL, 0x2CD99E8BUL, 0x5BDEAE1DUL,
    0x9B64C2B0UL, 0xEC63F226UL, 0x756AA39CUL, 0x026D930AUL,
    0x9C0906A9UL, 0xEB0E363FUL, 0x72076785UL, 0x05005713UL,
    0x95BF4A82UL, 0xE2B87A14UL, 0x7BB12BAEUL, 0x0CB61B38UL,
    0x92D28E9BUL, 0xE5D5BE0DUL, 0x7CDCEFB7UL, 0x0BDBDF21UL,
    0x86D3D2D4UL, 0xF1D4E242UL, 0x68DDB3F8UL, 0x1FDA836EUL,
    0x81BE16CDUL, 0xF6B9265BUL, 0x6FB077E1UL, 0x18B74777UL,
    0x88085AE6UL, 0xFF0F6A70UL, 0x66063BCAUL, 0x11010B5CUL,
    0x8F659EFFUL, 0xF862AE69UL, 0x616BFFD3UL, 0x166CCF45UL,
    0xA00AE278UL, 0xD70DD2EEUL, 0x4E048354UL, 0x3903B3C2UL,
    0xA7672661UL, 0xD06016F7UL, 0x4969474DUL, 0x3E6E77DBUL,
    0xAED16A4AUL, 0xD9D65ADCUL, 0x40DF0B66UL, 0x37D83BF0UL,
    0xA9BCAE53UL, 0xDEBB9EC5UL, 0x47B2CF7FUL, 0x30B5FFE9UL,
    0xBDBDF21CUL, 0xCABAC28AUL, 0x53B39330UL, 0x24B4A3A6UL,
    0xBAD03605UL, 0xCDD70693UL, 0x54DE5729UL, 0x23D967BFUL,
    0xB3667A2EUL, 0xC4614AB8UL, 0x5D681B02UL, 0x2A6F2B94UL,
    0xB40BBE37UL, 0xC30C8EA1UL, 0x5A05DF1BUL, 0x2D02EF8DUL,
};

/*
 * uint32_t crc_32( const unsigned char *input_str, size_t num_bytes );
 *
 * The function crc_32() calculates in one pass the common 32 bit CRC value for
 * a byte string that is passed to the function together with a parameter
 * indicating the length.
 */

uint32_t crc_32( const unsigned char *input_str, size_t num_bytes ) {

	uint32_t crc;
	const unsigned char *ptr;
	size_t a;

	crc = CRC_START_32;
	ptr = input_str;

	if ( ptr != NULL ) for (a=0; a<num_bytes; a++) {

		crc = (crc >> 8) ^ crc_tab32[ (crc ^ (uint32_t) *ptr++) & 0x000000FFul ];
	}

	return (crc ^ 0xFFFFFFFFul);

}  /* crc_32 */

/*
 * uint32_t update_crc_32( uint32_t crc, unsigned char c );
 *
 * The function update_crc_32() calculates a new CRC-32 value based on the
 * previous value of the CRC and the next byte of the data to be checked.
 */

uint32_t update_crc_32( uint32_t crc, unsigned char c ) {

	return (crc >> 8) ^ crc_tab32[ (crc ^ (uint32_t) c) & 0x000000FFul ];

}  /* update_crc_32 */
